drm/i915/gt: Clear LOCAL_BIND from shared GGTT on resume

We only restore GLOBAL binds upon resume as we expect these to be pinned
for use by HW, whereas the LOCAL binds can be recreated on demand once
userspace is resumed. For the LOCAL bind to be recreated in the global
GTT (for old systems without ppgtt), we need to clear its presence flag
on deciding not to restore the mapping upon resume.

Fixes: bf0840cd ("drm/i915/gt: Stop cross-polluting PIN_GLOBAL with PIN_USER with no-ppgtt")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200526150739.26147-1-chris@chris-wilson.co.uk